What Percentage of Peroxide to Use for Houseplant Soil

Plant roots breathe oxygen.

Healthy houseplants have healthy roots, and oxygen is needed for root health. Adding hydrogen peroxide to your plants' water can increase the amount of oxygen available in the soil. A colorless liquid, hydrogen peroxide (chemical formula, H2O2) breaks down in soil to its components, water, H2O, and a free radical oxygen, O. The extra oxygen can have big benefits when applied to the soil of houseplants. Add 1 1/3 to 2 1/2 teaspoons of 3 percent hydrogen peroxide to 1 gallon of water to make peroxided water.

Hydrogen Peroxide Percentages

Distributed through drug stores, grocery stores and other household product merchandizers, hydrogen peroxide comes in various strengths, such as 3, 5, 8 and 35 percent -- food grade. Percentages of 8 percent or lower are the safest for home use, as higher percentages can injure skin, and damage clothing and other items, according to Bryce Fredrickson in "Hydrogen Peroxide and Horticulture" on the Quick Grow website. If you use 35 percent peroxide, wear protective gloves and dilute the peroxide by adding one part peroxide to 11 parts distilled water, recommends Fredrickson. Dilute 5 percent peroxide to 3 percent by adding one part peroxide to 1 2/3 parts water, and dilute 8 percent peroxide to 3 percent by adding one part peroxide to 2 2/3 parts water.

Homemade Rainwater

One major difference between rainwater and tap water is rainwater's hydrogen peroxide content. Because rain picks up extra oxygen molecules from the ozone layer, some of the water molecules are turned into hydrogen peroxide molecules, according to researchers at the St. Francis College for Women, Alina Jyothi Joseph et al. Lightning also acts on oxygen to create hydrogen peroxide in rainwater, according to "Evidence for the Production of Hydrogen Peroxide in Rainwater by Lightning During Thunderstorms" by Yuegang Zuo and Yiwei Deng. When you add hydrogen peroxide to your tapwater or distilled water, you are adding the ingredient that has given rainwater its reputation for improving plant growth.

Peroxide Action in Soil

Peroxide breaks down rapidly in water, according to the hydrogen peroxide bulletin published by the Agency for Toxic Substances and Disease Registry. In soil, peroxide interacts with organic matter to break down matter and release nutrients. However, peroxide's disinfecting and antifungal properties are the main reason for increased growth of plants watered with peroxide, speculate Steven Sandtner and Charles Webber, as reported in their article published by the United States Department of Agriculture, "Hydrogen Peroxide as a Soil Amendment for Greenhouse Nasturtium Production."

Peroxide to the Rescue for Waterlogged Soil

Waterlogged soil smothers plant roots by filling air spaces, preventing the roots from getting oxygen. Wet soil and a wilted plant with a light green color are signs that the plant is waterlogged and its roots cannot get enough oxygen. If your plant hasn't suffered very long, you may be able to save it with peroxided water. Fredrickson recommends pouring peroxided water on the soil until water runs out of the bottom of the pot. Although this advice sounds counterintuitive, Fredrickson points out that peroxided water flushes out stagnant water and replaces it with oxygenated water, bringing this vital element to your plant's roots. Peroxide water also kills fungus and mold, which are common in waterlogged soil.

About the Author

For Judy Kilpatrick, gardening is the best mental health therapy of all. Combining her interests in both of these fields, Kilpatrick is a professional flower grower and a practicing, licensed mental health therapist. A graduate of East Carolina University, Kilpatrick writes for national and regional publications.